| 1. |
- Sturesson, Peter, 1981-, et al.
(author)
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Pirani Microgauge Fabricated of High-Temperature Co-fired Ceramics with Integrated Platinum Wires
- 2019
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In: Sensors and Actuators A-Physical. - : Elsevier BV. - 0924-4247 .- 1873-3069. ; 285, s. 8-16
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Journal article (peer-reviewed)abstract
- This paper presents the integration and pressure sensor operation of platinum bond wires in High-Temperature Co-fired alumina (HTCC). Devices were fabricated with a 50 μm diameter wire suspended across a 500 μm wide cavity in green-body state HTCC, electrically connected to screen printed alumina conductors. The substrate shrinkage during sintering to a cavity width of 400 μm causes the wire element to elevate from the cavity´s bottom surface. Resulting devices were compared with reference devices, containing screen-printed sensor elements, as Pirani gauges operated at 100 °C in constant-resistance mode, and in dynamic mode with a feeding current of 1 A in a pressure range from 10−4 Torr to atmospheric pressure. Also, devices with wire lengths between 500 and 3500 μm were operated and studied in constant-resistance and dynamic mode. Lastly, a device is demonstrated in operation at a mean temperature of 830 °C. The results include wire elements with a consistent elevation from their substrate surfaces, with irregularities along the wires. The wire devices exhibit a faster pressure response in dynamic mode than the reference devices do but operate similarly in constant-resistance mode. Increasing the wire element length shows an increasing dynamic pressure range but a decreasing maximum sensitivity. The sensitivity is retained in high temperature mode, but the dynamic range is extended from about 10 Torr to about 700 Torr.
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| 2. |
- Khaji, Zahra, et al.
(author)
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Investigation of the storage and release of oxygen in a Cu-Pt element of a high-temperature microcombustor
- 2014
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In: The 14th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications(PowerMEMS 2014). - : Institute of Physics (IOP).
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Conference paper (peer-reviewed)abstract
- A miniature combustor for converting organic samples into CO2 with application in carbon isotopic measurements has been manufactured and evaluated. The combustor was made of High-Temperature Co-fired Ceramic (HTCC) alumina green tapes. The device has a built-in screen printed heater and a temperature sensor made of platinum, co-sintered with the ceramic. A copper oxide oxygen supply was added to the combustor after sintering by in-situ electroplating of copper on the heater pattern followed by thermal oxidation. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Thermal Gravimetric Analysis (TGA) were used to study electroplating, oxidation and the oxide reduction processes. The temperature sensor was calibrated by use of a thermocouple. It demonstrates a temperature coefficient resistance of 4.66×10−3/°C between 32 and 660 °C. The heat characterization was done up to 1000 °C by using IR thermography, and the results were compared with the data from the temperature sensor. Combustion of starch confirmed the feasibility of using copper oxide as the source of oxygen of combustion.
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| 3. |
- Sturesson, Peter, 1981-
(author)
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Sense, Actuate and Survive : Ceramic Microsystems for High-Temperature Aerospace Applications
- 2018
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Doctoral thesis (other academic/artistic)abstract
- In aerospace applications, but also in manufacturing, mining, energy industry and natural hazards, high temperature, corrosion, erosion and radiation, challenge the performance and being of hardware.In this work, high-temperature co-fired ceramic (HTCC) alumina and platinum have been used for a range of devices intended for aerospace applications at up to 1000°C.The thermomechanics of a pressure sensor was investigated, and the interfacing was attained by wireless powering and reading. However, read range was limited and sensitivity decreased with temperature. Silver, electroplated after sintering, was found to remedy this until it eventually alloyed with platinum.Copper was electroplated and oxidized for oxygen storage in a microcombustor, intended for sample preparation for optogalvanic spectroscopy (OGS) to indicate extraterrestrial life. Despite delamination, caused by residual stresses, the device operated successfully.Conversely, pre-firing metallization by integration of platinum wires was studied. Freely suspended, and despite heat-induced shape irregularities, these were found advantageous over screen printed elements for gas heating, and temperature and pressure sensing. By fusing off the wires, spherical tips, allowing for impedance monitoring of microplasma sources in, e.g., OGS, were formed.Microplasma sources can also be used for gas heating. This, together with screen printed and suspended resistive heaters, was evaluated in a microthruster, showing that plasma heating is the most effective, implying fuel consumption reduction in satellite propulsion.In conclusion, HTCC alumina microdevices are thermally stable and could benefit several aerospace applications, especially with the complementary metallization schemes devised here.Future developments are expected to include both processing and design, all with the intention of sensing, actuating and surviving in high-temperature environments.
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| 4. |
- Persson, Anders, et al.
(author)
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Optogalvanic spectroscopy with microplasma sources – Current status and development towards lab on a chip
- 2016
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In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 26:10
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Journal article (peer-reviewed)abstract
- Miniaturized optogalvanic spectroscopy (OGS) shows excellent prospects of becoming ahighly sensitive method for gas analysis in micro total analysis systems. Here, a status reporton the current development of microwave induced microplasma sources for OGS is presented,together with the first comparison of the sensitivity of the method to conventional single-passabsorption spectroscopy. The studied microplasma sources are stripline split-ring resonators(SSRRs), with typical ring radii between 3.5 and 6 mm and operation frequencies around2.6 GHz. A linear response (R2 = 0.9999), and a stability of more than 100 s are demonstratedwhen using the microplasma source as an optogalvanic detector. Additionally, saturationeffects at laser powers higher than 100 mW are observed, and the temporal response of theplasma to periodic laser perturbation with repletion rates between 20 Hz and 200 Hz arestudied. Finally, the potential of integrating additional functionality with the detector isdiscussed, with the particular focus on a pressure sensor and a miniaturized combustor toallow for studies of solid samples.
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| 5. |
- Sturesson, Peter, 1981-, et al.
(author)
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Thermomechanical stability and integrability of an embedded ceramic antenna with an integrated sensor element for wireless reading in harsh environments
- 2013
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In: Journal of Physics: Conference Series. - London : IOP Publishing. - 1742-6588 .- 1742-6596.
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Conference paper (peer-reviewed)abstract
- This paper reports on the design, manufacturing and evaluation of a small, wirelessly powered and read resonating antenna circuit with an integrated pressure sensor. The work aims at developing miniature devices suitable for harsh environments, where high temperature prevents the use of conventional, silicon-based microdevices. Here, the device is made of alumina with platinum as conducting material. Ceramic green tapes were structured using high-precision milling, metallized using screen printing, and subsequently laminated to form stacks before they were sintered. The device's frequency shift as a function of temperature was studied up to 900°C. The contributions to the shift both from the thermomechanical deformation of the device at large, and from the integrated and, so far, self-pressurized sensor were sorted out. A total frequency shift of 3200 ppm was observed for the pressure sensor for heating over the whole range. Negligible levels of thermally induced radius of curvature were observed. With three-point bending, a frequency shift of 180 ppm was possible to induce with a curvature of radius of 220 m at a 10 N load. The results indicate that a robust pressure sensor node, which can register pressure changes of a few bars at 900°C and wirelessly transmit the signal, is viable.
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| 6. |
- Berglund, Martin, 1985-, et al.
(author)
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Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
- 2015
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In: Journal of Micromechanics and Microengineering. - Bristol : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 25:10
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Journal article (peer-reviewed)abstract
- This paper reports on a novel method for manufacturing microscopic Langmuir probes with spherical tips from platinum bond wires by fusing for plasma characterization in microplasma sources. Here, the resulting endpoints, formed by droplets on the ends of a fused wire, are intended to act as spherical Langmuir probes. For studying the fusing behavior, bond wires were wedge bonded over a 2 mm wide slit, to emulate the final application, and fused with different voltages and currents. For electrical isolation, a set of wires were coated with a 4 μm thick layer of Parylene before they were fused. After fusing, the gap size, as well as the shape and area of the ends of the remaining stubs were measured. The yield of the process was also investigated, and the fusing event was studied using a high-speed camera for analyzing its dynamics. Four characteristic tip shapes were observed: spherical, folded, serpentine shaped and semi-spherical. The stub length leveled out at ~400 μm as the fusing power increased. The fusing of the coated wires required a higher power to yield a spherical shape. Finally, a Parylene coated bond wire was integrated into a stripline split-ring resonator (SSRR) microplasma source, and was fused to form two Langmuir probes with spherical endpoints. These probes were used for measuring the I–V characteristics of a plasma generated by the SSRR. In a voltage range between −60 V and 60 V, the fused stubs exhibited the expected behavior of spherical Langmuir probes, and will be considered for further integration.
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| 7. |
- Khaji, Zahra, et al.
(author)
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Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element
- 2015
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In: Journal of Micromechanics and Microengineering. - Bristol : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 25:10
-
Journal article (peer-reviewed)abstract
- A microscale ceramic high-temperature combustor with a built-in temperature sensor and source of oxygen has been designed, manufactured and characterized. The successful in situ electroplating and oxidation of copper, and the use of copper oxide as the source of oxygen were demonstrated. It was shown that residual stresses from electroplating, copper oxidation and oxide decomposition did not cause much deformation of the substrate but influenced mainly the integrity and adhesion of the metal films. The process had influence on the electrical resistances, however. Calibration of the temperature sensor and correlation with IR thermography up to 1000°C revealed a nearly linear sensor behavior. Demonstration of combustion in a vacuum chamber proved that no combustion had occurred before release of oxygen from the metal oxide resource.
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| 8. |
- Knaust, Stefan, et al.
(author)
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Characterization of dielectric properties of polycrystalline aluminum nitride for high temperature wireless sensor nodes
- 2013
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In: Journal of Physics. - London : Institute of Physics (IOP).
-
Conference paper (peer-reviewed)abstract
- An aluminium nitride (AlN) passive resonance circuit intended for thermallymatched high temperature wireless sensor nodes (WSN) was manufactured using thick-lmtechnology. Characterization was done for temperatures up to 900C in both a hot-chuck forfrequencies below 5 MHz, and using wireless readings of resonating circuits at 15 MHz, 59 MHz,and 116 MHz. The substrate for the circuits was sintered polycrystalline AlN. Using a simpliedmodel for the resonators where the main contribution of the frequency-shift was considered tocome from a shift of the dielectric constant for these frequencies, the temperature dependency ofthe dielectric constant for AlN was found to decrease with increasing frequency up to 15 MHz.With an observed frequency shift of 0.04% at 15 MHz, and up to 0.56% at 59 MHz over atemperature range of 900C, AlN looks as a promising material for integration of resonancecircuits directly on the substrate.
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| 9. |
- Sturesson, Peter, 1981-, et al.
(author)
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Ceramic Pressure Sensor for High Temperatures – Investigation of the Effect of Metallizationon on Read Range
- 2017
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In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 17:8, s. 2411-2421
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Journal article (peer-reviewed)abstract
- A study on the relationship between circuit metallization, made by double-layer screen printing of platinum and electroplating of silver on top of platinum, and its impact on practical read range of ceramic LC resonators for high-temperature pressure measurements is presented. Also included is the first realization of membranes by draping a graphite insert with ceramic green body sheets. As a quality factor circuit reference, two-port microstrip meander devices were positively evaluated and to study interdiffusion between silver and platinum, test samples were annealed at 500 degrees C, 700 degrees C, and 900 degrees C for 4, 36, 72, and 96 h. The LC resonators were fabricated with both metallization methods, and the practical read range at room temperature was evaluated. Pressure-sensitive membranes were characterized for pressures up to 2.5 bar at room temperature, 500 degrees C and up to 900 degrees C. Samples electroplated with silver exhibited performance equal to or better than double-layer platinum samples for up to 60 h at 500 degrees C, 20 h at 700 degrees C, and for 1 h at 900 degrees C, which was correlated with the degree of interdiffusion as determined from cross-sectional analysis. The LC resonator samples with double-layer platinum exhibited a read range of 61 mm, and the samples with platinum and silver exhibited a read range of 59 mm. The lowest sheet resistance, and, thereby, the highest read range of 86 mm, was obtained with a silver electroplated LC resonator sample after 36 h of annealing at 500 degrees C.
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| 10. |
- Sturesson, Peter, 1981-, et al.
(author)
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Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster
- 2019
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In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 28:2, s. 235-244
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Journal article (peer-reviewed)abstract
- The research and development of small satellites has continued to expand over the last decades. However, the propulsion systems with adequate performance have persisted to be a great challenge. In this paper, the effects of three different heaters on the specific impulse and overall thrust efficiency of a cold gas microthruster are presented. They consisted of a conventional, printed resistive thick-film element, a freely suspended wire, and a stripline split-ring resonator microplasma source, and were integrated in a single device made from the high-temperature co-fired ceramics. The devices were evaluated in two setups, where the first measured thrust and the other measured shock cell geometry. In addition, the resistive elements were evaluated as gas temperature sensors. The microplasma source was found to provide the greatest improvement in both specific impulse and thrust efficiency, increasing the former from an un-heated level of 44–56 s when heating with a power of 1.1 W. This corresponded to a thrust efficiency of 55%, which could be compared with the results from the wire and printed heaters which were 51s and 18%, and 45s and 14%, respectively. The combined results also showed that imaging the shock cells of a plasma heated thruster was a simple and effective way to determine its performance, when compared to the traditional thrust balance method.
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